An inkjet printing system typically includes one or more printheads and their corresponding ink supplies. Each printhead includes an ink inlet that is connected to its ink supply and an array of drop ejectors, each ejector consisting of an ink pressurization chamber, an ejecting actuator and a nozzle through which droplets of ink are ejected. The ejecting actuator may be one of various types, including a heater that vaporizes some of the ink in the pressurization chamber in order to propel a droplet out of the orifice, or a piezoelectric device which changes the wall geometry of the chamber in order to generate a pressure wave that ejects a droplet. The droplets are typically directed toward paper or other recording medium in order to produce an image according to image data that is converted into electronic firing pulses for the drop ejectors as the recording medium is moved relative to the printhead.
A common type of printer architecture is the carriage printer, where the printhead nozzle array is somewhat smaller than the extent of the region of interest for printing on the recording medium and the printhead is mounted on a carriage. In a carriage printer, the recording medium is advanced a given distance along a media advance direction and then stopped. While the recording medium is stopped, the printhead carriage is moved in a direction that is substantially perpendicular to the media advance direction as the drops are ejected from the nozzles. After the carriage has printed a swath of the image while traversing the recording medium, the recording medium is advanced; the carriage direction of motion is reversed, and the image is formed swath by swath.
The ink supply on a carriage printer can be mounted on the carriage or off the carriage. For the case of ink supplies being mounted on the carriage, the ink tank can be permanently integrated with the printhead as a print cartridge, so that the printhead needs to be replaced when the ink is depleted, or the ink tank can be detachably mounted to the printhead so that only the ink tank itself needs to be replaced when the ink tank is depleted. Carriage mounted ink supplies typically contain only enough ink for up to about several hundred prints. This is because the total mass of the carriage needs be limited so that accelerations of the carriage at each end of the travel do not result in large forces that can shake the printer back and forth. As a result, users of carriage printers need to replace print cartridges periodically depending on their printing usage, typically several times per year. Consequently, the task of replacing a detachably mounted print cartridge must be simple and must consistently achieve a proper engagement of the print cartridge with the carriage. Otherwise, improper mounting of the print cartridge can lead to misalignment of the nozzle arrays with respect to the media advance direction causing jaggedness in printed images. In addition an improperly mounted print cartridge can have intermittent electrical contact with printer, which results in poor image quality or even damage to the print cartridge.
US Patent Application Publication 2008/0151032, incorporated herein by reference, discloses an ink tank having a data storage device mounted on a pedestal such that the pedestal can extend through an opening in a supporting structure of the printhead. As such, when the printhead is mounted on the carriage, and the ink tank is installed in the printhead, the data storage device on the ink tank pedestal makes contact with an electrical connector on the carriage. As a result, the printer can detect that an ink tank has been installed. In an analogous fashion, a print cartridge can have a device or electrical contacts to make contact with an electrical connector on the carriage so that the printer senses installed print cartridges. However, on some occasions, it is found that the user accidentally does not fully press the print cartridge into its latched position on the carriage, but the data storage device still touches the electrical contact on the carriage. Thus, the printer falsely detects a properly installed print cartridge, when in fact the print cartridge is improperly installed.
What is needed is a user-friendly mounting configuration that eliminates false indications of print cartridge installations while enabling reliable detection of properly mounted print cartridges.